So-called "Oetiker" ears as tightening means have enjoyed an immense success worldwide because of the ability to "breathe", i.e., compensate for thermal expansions, increase of pressure in the hose and aging of the hose without loss of the holding ability of the clamp. As described in U.S. Pat. No. 3,082,498, the typical "Oetiker" ear generally designated by reference numeral 2 (FIG. 1) of a so-called closed clamp generally designated by reference numeral 1 includes two parallel, outwardly extending leg portions 3 and 4 interconnected by a bridging portion 5, whereby the ear, when plastically deformed, assumes a more or less omega shape (FIG. 2). To avoid the need for special tools to achieve the desired omega shape in every case, a reinforcing groove 40' (FIG. 3) extending in the circumferential direction of the bridging portion 5 as described in U.S. Pat. No. 3,402,436 has been used in both so-called closed clamps as well as in so-called open clamps. Its use in so-called open clamps is shown in FIG. 4 which represents a clamp as described in U.S. Pat. No. 4,299,012 which includes in its improved mechanical connection a guide hook 31 and two cold-deformed, deep drawn support hooks 32 adapted to engage in apertures 35. This clamp is also provided with an arrangement achieving an inner clamping surface devoid of any step, discontinuity or gap and includes a tongue-like extension 61 adapted to engage in a central channel 63 beginning at the step-like portion 67 and terminating in the second step-like portion 65. An improved reinforcing means in the form of a shallow pan-shaped depression 40" with a substantially flat bottom and extending over a wide area of the bridging portion (FIG. 5) eventually replaced the reinforcing groove 40', as described in U.S. Pat. No. 5,305,499. Clamps with so-called "Oetiker" ears incorporating the aforementioned features are presently being used annually in large numbers involving hundreds of millions.
Because clamps with "Oetiker" ears, once installed, cannot be removed without destruction of the ear, it is important that the clamping tool be properly positioned relative to the ear and clamp before tightening the clamp by plastic deformation of the ear. On the assembly line, commercially available pneumatic tools are used to contract the clamp with essentially the same force. Though relatively rarely, operators using pneumatically actuated pincer-like tools, apply the tool incorrectly on the assembly line under pressure of time, i.e., fail to engage the tips of the jaws of the tool in the area of connection between the band portions and the outwardly extending leg portions of the ear which may result in an improperly installed clamp. The part then has to be removed, requiring sidelining the particular part with the incorrectly installed clamp, removing the clamp by destruction and radially installing a new clamp.
Another problem encountered with clamps is the ever-growing demand to increase the tolerance range of the clamp, i.e., to compensate for dimensional deviations of the hose and/or of the fixed member, such as a nipple, which the clamp of a given size can cover to fasten the hose reliably to the fixed member.